High frequency model of power autotransformer for adjustable speed drive system

This paper presents a high frequency model of a 20 kVA power autotransformer, used for power system studies. Based on the low frequency equivalent circuit of the power autotransformer, which is built with vector fitting method, several RL and RC branches are introduced to reflect the high frequency performance of the autotransformer. With the comparison of calculated and measured impedances of the autotransformer, the effectiveness of the proposed model is verified.